From what I know the depth rating is supposed to be the same as the stock housing so 60m/200ft, only other spec Ive heard of is its claimed to be vignette free in all modes. That's why they have gone the square design and slightly cut around the power button which is what limits the Blurfix, and Backscatter type designs to 55mm and so slight vignette in 960p and wide photo underwater.
From my experience with Flat lenses and multiple GoPro's and housings the loose manufacturing tolerance could possibly still cause a slight vignette on land in 960p or wide photo in some rare Housing and camera combinations. Ive seen this with the Blurfix where one of my HD2's and one housing has a very slight vignette on land in wide 1080p or 720p mode but is vignette free with my other camera and housings. Underwater though they are all vignette free and so this should be too, with the slightly larger size it should be all clear underwater though easily.
No word on filters and GoPro generally keep unreleased products very quite, some info has leaked out over the last year and a pic was first seen mid last year from the dema show, I dont know what could possibly have caused the long delay for release as it still looks the same if this is a recent pic.